Fragrance materials are used in numerous products to enhance the consumer's enjoyment of a product. Fragrance materials are added to consumer products such as laundry detergents, fabric softeners, soaps, detergents, personal care products, such as shampoos, body washes, deodorants and the like, as well as numerous other products.
To enhance the effectiveness of the fragrance materials for the user, various technologies have been employed to enhance the delivery of the fragrance materials at the desired time. One widely used technology is encapsulation of the fragrance material in a protective coating. Frequently the protective coating is a polymeric material. The polymeric material is used to protect the fragrance material from evaporation, reaction, oxidation or otherwise dissipating prior to use. For example, U.S. Pat. No. 4,081,384 discloses a softener or anti-stat core coated by a polycondensate suitable for use in a fabric conditioner. U.S. Pat. No. 5,112,688 discloses selected fragrance materials having the proper volatility to be coated by coacervation with microparticles in a wall that can be activated for use in fabric conditioning. U.S. Pat. No. 5,145,842 discloses a solid core of a fatty alcohol, ester, or other solid plus a fragrance coated by an aminoplast shell. U.S. Pat. No. 6,248,703 discloses various agents including fragrance in an aminoplast shell that is included in an extruded bar soap.
It is typically not desired that the encapsulated materials be released from the shell prematurely. Often, the capsule shell is somewhat permeable to the core contents when stored under certain conditions. This is particularly the case when many capsule types, such as those having aminoplast or cross-linked gelatin walls, are stored in aqueous bases, particularly those containing surfactants. In these cases, although the capsule shell is intact, the active material is diffused from the core over time in a leaching process. The overall leaching mechanism may be viewed as a diffusion process, with transfer occurring from the capsule core to the aqueous media, followed by transfer to or solubilization into the surfactant micelles or vesicles. With normal surfactant concentrations of between 1 and 50% in consumer products, as compared to active material levels of 0.3 to 1%, it is clear that the partitioning favors absorption by the surfactant over time.
There is also a need in the art to provide a microcapsule product with improved cost-in-use performance so that consumer product companies can use less microcapsule product to obtain equal or better performance/benefit.